SULFONATED ESTER OLIGOMERS SUITABLE AS DISPERSING AGENTS IN DETERGENT COMPOSITIONS

Abstract: Fully and partially oligomerized anionic esters useful as dispersing agents in detergent compositions. The esters comprise terephthalate units, oxy-1,2-alkyleneoxy units (oxyethyleneoxy units preferred), and sulfoisophthalate units.

Description: SULFONATED ESTER OUGOMERS SUITABLE AS DISPERSING AGENTS IN DETERGENT COMPOSITIONS TECHNICAL FIELD The present invention relates to anionic ester compositions useful as soil dispersing agents in fabric care compositions, especially liquid and granular laundry detergent compositions and synthetic laundry bar detergents. CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Serial Number 08/044,995, filed April 7, 1993. BACKGROUND OF THE INVENTION It has long been known that a need exists for detergent compositions which provide superior cleaning benefits on heavily soiled textiles and fabrics and which disperse and suspend soils in the laundry liquor to prevent their redeposition onto the fabrics. This is especially true for organic soils and stains, such as those formed by industrial pollution, body soils and/or automobile exhaust. Fabrics exposed to such heavy soiling can often have a dull gray or dingy look even after washing. In many instances the consumer re-uses the laundry liquor for several wash loads. During the wash cycle, the soils and stains that are removed from the fabrics become concentrated in the laundry liquor and redeposit onto the fabrics before they can be removed from the wash. The redeposited soils also contribute to the dull and dingy appearance. The problem is compounded by the laundering methods used by many consumers wherein the fabrics are typically washed with the use of granular detergents or detergent bars in a low water to fabric ratio, i.e., wherein the ratio of water:fabric load is substantially less than in automatic laundry machines. This is especially true under hand-wash conditions, but also occurs in concentrated washing processes, such as those disclosed in U.S. Patents 4,489,455 and 4,489,574, both issued to Spendel on Dec. 25, 1984. A number of dispersing or antiredeposition compounds are known to be effective in detergent compositions, particularly for inorganic particulates such as clay. However, to date, these compounds have not been found to be effective under conditions of heavy, organic soiling wherein the soils become highly concentrated in the laundry liquor. Another component of modern conventional detergent composi¬ tions is soil release agents (s.r.a.'s). It is believed that s.r.a.'s deposit on the fabric surface, particularly polyester fabrics, during the laundry cycle. As the fabrics are used or worn, soils collect on the treated fabric surface. When the fabric is re-laundered, the s.r.a.'s aid in the removal of these soils from the fabric's surface. A wide variety of soil release agents for use in in-home fabric treatment processes are known in the art. Various s.r.a.'s have been commercialized and are currently used in detergent compositions and fabric softener/antistatic articles and composi¬ tions. Anionic s.r.a.'s typically comprise an oligoester backbone, which may itself optionally contain various anionic substituents, and will usually terminate with one or more end-capping units which are also anionic. For example, various oxyalkylene/terephtha- late/sulfoisophthaloyl oligomers end-capped with sulfoaroyl substi¬ tuents comprise a known and important class of s.r.a.'s for use in laundry detergents. One major difference between s.r.a.'s and the oligomer compositions of this invention is that s.r.a.'s require multi-cycle laundering to provide benefits. Through multiple launderings the s.r.a.'s are deposited onto the fabric surface. It is only after the s.r.a.'s have been deposited onto the fabric that the s.r.a.'s aid in the cleaning process. In contrast, the dispersing agents of this invention are not required to deposit on the fabric surface; cleaning benefits are, therefore, provided even during the first laundry cycle before the fabrics have been previously contacted with the dispersing agent. By the present invention, it has now been discovered that certain anionic oligomer compositions similar to those employed as s.r.a.'s, especially those of low molecular weight and incomplete oligo erization, can be employed as dispersing agents. Such dispersing agents have been found to be especially effective under conditions of heavy fabric soiling. Without wishing to be limited by theory, it is believed that the oligomer compositions disperse and suspend the soil in the laundry liquor and prevent the soil from redepositing onto the fabric surface. Accordingly, the laundered fabrics have a brighter, less dingy appearance, even after the first laundry cycle. The present invention thus solves the long-standing need for an effective dispersing agent which provides a novel method of brightening fabrics by suspending organic soils in the laundry liquor and preventing their redeposition onto the fabric surface. The dispersing agents are particularly effective in liquid or granular detergent compositions and synthetic detergent bars for use in hand-wash, or under other circumstances where low water to fabric ratios are used in a laundering operation. These and other objects are secured herein as will be seen from the following disclosure. BACKGROUND ART U.S. Patent 4,702,857, Gosselink, issued October 27, 1987, discloses block polyester esters and mixtures thereof useful as soil release agents in detergent compositions. See also U.S. Patent 4,861,512. U.S. Patent 4,721,580, Gosselink, issued January 26, 1988, discloses end-capped oligomeric esters and mixtures thereof for use as soil release agents in detergent compositions. See also U.S. Patent 4,968,451 and U.S. Patent 4,877,896. Polyesters have also been disclosed for use in rinse-added consumer laundry products, in dryer-added products, and in certain built liquid detergents. See Canadian Patent 1,100,262, Becker et al, Issued July 8, 1975; U.S. Patent 3,712,873, Zenk, issued January 23, 1973; U.S. Patent 4,238,531, Rudy et al , issued December 9, 1980; and British Patent Application 2,172,608, Crossin, published September 24, 1986. Types of synthetic and analytical methods useful- herein are well illustrated in European Patent Application 185,427, Gosselink, published June 25, 1986, and in Odian, Principles of Polymerization. Wiley, NY, 1981. Chapter 2.8 of the Odian reference, entitled "Process Conditions", pp 102-105, focuses on the synthesis of pol (ethylene terephthalate). SUMMARY OF THE INVENTION The present invention encompasses a method for cleaning fabrics, said method comprises contacting said fabrics in an aqueous liquor comprising conventional detergent ingredients and oligo eric, substantially linear ester compositions useful as dispersing agents. The detergent ingredients can optionally comprise detergent builders and other conventional detersive adjuncts in a liquid, granular or laundry bar detergent composi¬ tion. The method also encompasses presoaking soiled fabrics before washing. The detergent compositions employed in the present invention may even be used for overnight soaking of the laundry. Therefore, the preferred method of laundering involves contacting fabric or textiles with an aqueous laundry liquor comprising a detergent composition which comprises at least about 300 ppm, preferably from about 300 ppm to about 20,000 ppm, of conventional detersive ingredients and at least about 1 ppm, preferably from about 1 ppm to about 50 ppm, of said dispersing agent for about 5 minutes to about 15 hours. When the detersive ingredients comprise a detersive surfactant, the ratio of dispersing agent to surfactant should preferably be below about 1:10. The washing operation preferably employs agitating the fabrics with an aqueous liquor containing the compositions herein. The fabrics can then be rinsed with water and line or tumble dried. The dispersing agents are especially effective under typical hand-wash conditions or in low water to fabric load laundering situations wherein the ratio of fabricrwater (kg:liters) ranges from about 1:15 to about 1:0.5, especially from about 1:7 to about 1:1. A typical ratio under hand-wash conditions is about 1:5. The dispersing agents herein comprise ester compositions with relatively low Completion Indices and relatively low molecular weights (i.e., below the range of fiber-forming polyesters). Typical dispersing agents of the present invention have a number average molecular weight ranging from about 400 to about 3,000. Said ester compositions employed herein comprise oxyethyleneoxy or oxy-l,2-propyleneoxy units and terephthaloyl units. Preferred ester compositions additionally comprise sulfoisophthalate and sulfonated end-capping units. (Mixtures of such esters with reaction by-products and the like retain their utility as soil dispersing agents when they contain a minimum of doubly end-capped esters.) Taken in their broadest aspect, the ester compositions provided by this invention encompass a mixture of oligomeric esters comprising "backbones" which are optionally end-capped on one or both ends of the backbone by end-capping units. Preferably, the esters are not fully oligomerized, i.e., doubly end-capped. The relative ratio of fully oligomerized to partially oligomerized ester molecules in a given composition can be related to its Completion Index (defined hereinafter). The end-capping units herein are anionic sulfonated hydro- philes and connected to the esters by an ester linkage. The pre¬ ferred end-capping units are selected from the group consisting of: a) Mθ3S(CH2)m( H2CH2θ)(RO) n -, wherein M is a salt-forming cation such as sodium or tetraalkylammonium, R is ethylene or propylene or a mixture thereof, m is 0 or 1, and n is from 0 to 4; b) sulfobenzoyl units of the formula (Mθ3S)(C6H )C(0)-, wherein M is a salt-forming cation; and c) mixtures of a) and b). Certain noncharged, hydrophobic aryldicarbonyl units are essential in the backbone unit of the oligoesters herein. Preferably, these are exclusively terephthaloyl units. Other noncharged, hydrophobic aryldicarbonyl units, such as isophthaloyl or the like, can also be present if desired, provided that the soil dispersing benefits of the esters are not significantly diminished. It is also possible optionally to incorporate additional hydrophllic units into the esters. For example, anionic hydrophilic units capable of forming two ester bonds may be used. Suitable anionic hydrophilic units of this specific type are well illustrated by sulfonated dicarbonyl units, such as sulfoisophthal- oyl, i.e., -(0)C(C6H3)(Sθ3M)C(0)-, wherein M is a salt-forming cation such as an alkali metal or tetraalkylammonium ion. Thus, preferred dispersing agents herein comprise mixtures of: A) from 0% to about 95% of fully oligomerized (di-capped) esters of the formula: (CAP)2(EG/PG)v(T) y (SI) 2 wherein i) (CAP) represents sulfonated end-capping units selected from the group consisting of: (a) Mθ3S(CH 2 ) m (CH 2 CH2θ)(RO) n -, wherein M is a salt-forming cation, R is ethylene or propylene or a mixture thereof, m is 0 or 1, and n is from 0 to 4; (b) sulfobenzoyl units of the formula (Mθ3S)(C6H4)C(0)-, wherein M is a salt-forming cation; and (c) mixtures of (a) and (b); ii) (EG/PG) represents oxyethyleneoxy units, oxy-l,2-ρropyl- eneoxy units or mixtures thereof; iii) (T) represents terephthaloyl units; and, optionally, iv) (SI) represents 5-sulfoisophthaloyl units of the formula -(0)C(C6H3)(S03M)C(0)-, wherein M is a salt-forming cation; v is from about 0.25 to about 50, y is from about 1.25 to about 30, preferably from about 1.5 to about 8, and z is determined by the formula y/(z+l) - about 1.25 to about 5; wherein, v, y and z represent the average number of moles of the corresponding units per mole of said ester; and B) from about 5% to 100% of partially oligomerized esters of A) with a number average molecular weight of no more than 70% of the molecular weight of the fully oligomerized esters, A); such that the number average molecular weight of the dispersing agent is from about 400 to about 3,000, preferably from about 500 to about 1,100, and most preferably from about 600 to about 900. Preferably, when the (CAP) units are i)(a), v is determined by the formula v - y+z to y+z-1. When the (CAP) units are i)(b), v is determined by the formula v « y+z+1, and when the (CAP) units are i)(c) » v is determined by the formula v ■ y+z+1. The preferred esters have a number average molecular weight of no more than 70%, preferably from about 10% to about 60%, of the formula weight of the fully oligomerized or "target" structure. In calculating the number average molecular weight of the compositions only the ester components are included and not any residual free glycols which may also be present. The degree of oligomerization necessary to achieve the desired percent of target formula weight can be related to a Completion Index. Ester compositions of the invention will comprise at least about 5%, preferably at least about 10% and most preferably at least about 50%, of partially oligomerized esters. A fully oligomerized ester will be doubly end-capped and will have a Completion Index of infinity. The ester "backbone" of the present compositions, by defini¬ tion, comprises all the units other than the end-capping units. All the units incorporated into the esters being interconnected by means of ester bonds. Thus, in one simple embodiment the ester "backbones" comprise only terephthaloyl units and oxyethyleneoxy units. In preferred embodiments incorporating oxy-l,2-propylene- oxy units, the ester "backbone" comprises terephthaloyl units, oxyethyleneoxy, and oxy-l,2-propyleneoxy units. In still other highly preferred embodiments, hydrophilic units such as 5-sulfo- isophthalate are present in the backbone wherein the preferred ratio of terephthaloyl to 5-sulfoisophthaloyl units is determined by the formula y/(z+l) » 2 to 4, wherein y and z are defined above. The ester compositions herein comprise at least 50% by weight of said ester oligomers having a number average molecular weight ranging from about 400 to about 3,000. The invention also encompasses the preparation of dispersing agents characterized in that they consist essentially of the oligomeric product of reacting dimethyl terephthalate or terephthalic acid, ethylene glycol, propylene glycol or a mixture thereof, a compound selected from the group consisting of monovalent cation salts of sulfonated end-capping monomers and, optionally, dimethyl sodiosulfoisophthalate or sulfoisophthalic acid, monosodium salt. The resulting water-soluble oligomeric products are useful for dispersing soils in an aqueous laundry liquor. A preferred dispersing agent is prepared by reacting 1 mole of monovalent cation salts of sulfonated end-capping monomers, 5 moles of dimethyl terephthalate, 1 mole of dimethyl sulfoisophthalate, and 12 moles of ethylene glycol, propylene glycol or mixtures thereof. The conventional detergent ingredients used in the present invention comprise from about 1% to about 99.9%, preferably from about 5% to about 80%, of a detersive surfactant. Optionally, the detergent ingredients comprise from about 5% to about 80% of a detergent builder. Other optional detersive adjuncts can also be included in such compositions, at conventional usage levels. The dispersing agents will typically constitute from about 0.1% to about 10%, preferably from about 0.25% to about 5%, by weight of detergent composition. All percentages, ratios, and proportions herein are on a weight basis unless otherwise indicated. All documents cited are incorporated herein by reference. DETAILED DESCRIPTION OF THE INVENTION The essential component of the compositions employed in the present invention is a dispersing agent comprising a mixture of fully and partially oligomerized esters characterized by certain essential backbone units and optional end-capping units, all in particular proportions and having structural arrangements as described hereinafter. The following structures are illustrative, but by no means limiting, of preferred structures of ester molecules of the invention. The target structure of a fully oligomerized ester has the formula: -(C6H4)Sθ3Na The preferred partially oligomerized ester employed in the present invention will have about 50% of the formula weight of the above target ester and a Completion Index of about 6. In another example, the target structure is: The preferred partially oligomerized ester employed in the present invention will have about 40% to 50% of the formula weight of the above target ester and a Completion Index of about 3. In still another example, the target structure is: 2S03Na The preferred partially oligomerized ester employed in the present invention will have about 20% of the formula weight of the above target ester and a Completion Index of about 1.8. The esters herein can be simply characterized as oligomers which comprise a substantially linear ester "backbone" and, optionally, one or more kinds of end-capping units, especially 2-(2-oxyethoxy)ethanesulfonate or sulfobenzoyl. Proper selection of the structural units which comprise the ester backbone, use of sufficient amounts of the sulfonated end-capping units, and control of the degree of oligomerization results in the desired soil dispersing benefits provided by these materials. Degree of Oligomerization - It is to be understood that the compositions herein are not resinous, high molecular weight, macromolecular or fiber-forming polyesters but, instead, are relatively low molecular weight and contain species more ap¬ propriately described as oligomers rather than as polymers. Ester molecules herein, including the end-capping units, can have number average molecular weights ranging from about 400 to about 3,000. Relevant for purposes of comparison with glycol-terephthalate fibrous polyesters (typically averaging 15,000 or more in molecular weight) is the molecular weight range of from about 500 to about 1,100, within which preferred molecules of the esters of the invention which incorporate the essential units are generally found. Accordingly, the compositions of this invention are referred to as "oligomeric esters" rather than "polyester" in the colloquial sense of that term as commonly used to denote high polymers such as fibrous polyesters. Molecular Geometry - The esters of the invention are all "substantially linear" in the sense that they are not significantly branched or crosslinked by virtue of the incorporation into their structure of units having more than two ester-bond forming sites. (By contrast, for a typical example of polyester branching or crosslinking of the type excluded in defining esters of the present invention, see Sinker et al , U.S. Patent 4,554,328, issued November 19, 1985.) Furthermore, no cyclic esters are essential for the purposes of the invention but may be present in the compositions of the invention at low levels as a result of side-reactions during ester synthesis. Preferably, cyclic esters will not exceed about 2% by weight of the compositions; most preferably, they will be entirely absent from the compositions. Contrasting with the above, the term "substantially linear" as applied to the esters herein does, however, expressly encompasses materials which contain side-chains which are unreactive in ester-forming or transesterification reactions. Thus, oxy-1,2- propyleneoxy units are of an unsy metrically substituted type; their methyl groups do not constitute what is conventionally regarded as "branching" in polymer technology (see Odian, Principles of Polymerization, Wiley, N.Y., 1981, pages 18-19, with which the present definitions are fully consistent) and are unreactive in ester-forming reactions. Optional units in the esters of the invention can likewise have side-chains, provided that they conform with the same nonreactivity criterion. Molecular Units - The esters of this invention comprise end-capping units and repeating backbone units. To briefly illustrate an embodiment of the invention, molecules of the ester are comprised of three kinds of units, namely: i) sulfonated end-capping units selected from, the group consisting of: (a) Mθ3S(CH2) m (CH2CH2θ)(RO) n -, wherein M is a salt-forming cation, R is ethylene or propylene or a mixture thereof, m is 0 or 1, and n is from 0 to 4; (b) sulfobenzoyl units of the formula (Mθ3S)(C6H4)C(0)-, wherein M is a salt-forming cation; and (c) mixtures of (a) and (b); ii) oxyethyleneoxy backbone units, i.e., -OCH2CH2O-, oxy-l,2-propyleneoxy units, i.e., -OCH(CH3)CH2θ- or -OCH2CH(CH3)0- or mixtures thereof; and iii) terephthaloyl backbone units, i.e., -(0)CCgH4C(0)-. Optionally but preferably, the esters herein also contain anionic hydrophilic units in the backbone. These units most preferably are: iv) 5-sulfoisophthaloyl backbone units of the formula -(0)C(C6H3)(S03M)C(0)-, wherein M is a salt-forming cation. The following structures are illustrative of structures of ester molecules falling within the foregoing embodiments and demonstrate how the units are connected: a) doubly end-capped ester molecule comprised of the units i), ii) and iii); b) siinnggTlyy end-capped ester molecule comprised of units i), ii) and iii); 0-CH2CH2-0-C ? : y)-C-0-CH2CH2-0H c) singly end-capped ester molecule, (termed a "hybrid backbone" ester molecule herein) comprised of units i), ii) and ill). Units ii) are a mixture of oxyethyleneoxy and oxy-1,2- propyleneoxy units, in the example shown below at a 3:1 mole ratio; 0 0 0 0 . Naθ3SCH2CH2θCH2CH2-0-C- Q)-C-OCH2CH2θ-C- ζ5 -C- 0 0 0 0 -OCH2CH2θ-C- θy c"0"CH 2 CH ( CH 3)- 0 - c -O C"OCH2CH2 ° H d) singly end-capped ester molecule comprised of units i), ii), iii) and iv); Sθ3Na CH2CH(CH3) -OH In the context of the structures of ester molecules disclosed herein it should be recognized that the present invention encompasses not only the arrangement of units at the molecular level, but also the gross mixtures of esters which result from the reaction schemes herein and which have the desired range of composition and properties. Accordingly, when the number of monomer units or ratios of units are given, the numbers refer to an average quantity of monomer units present in oligomers of the composition. Ester Backbone - As illustrated in the structures shown above, in the esters employed herein, the backbone is formed by oxyethyleneoxy and/or oxypropyleneoxy and terephthaloyl units connected in alternation. Optionally, the backbone is formed by 5-sulfoisophthaloyl units, terephthaloyl units, oxyethyleneoxy and/or oxypropyleneoxy units connected with alternation of the aryldicarbonyl and oxyalkyl^neoxy units. It should be recognized that polyoxyethyleneoxy units, especially di(oxyethylene)oxy units, formed during synthesis of the esters, can be present in trace amounts in the backbone. Groups at the Termini of the Ester Backbone - Likewise, the "esters employed herein" is a term which encompasses the doubly and singly end-capped compounds disclosed herein, mixtures thereof, and mixtures of said end-capped materials with non-capped species. Thus, when referring simply to an "ester" herein it is intended to refer, by definition, collectively to the mixture of sulfonated capped and uncapped ester molecules resulting from any single preparation. Any ester molecules which are present in compositions of the invention which are not fully, i.e., doubly, end-capped by the end- capping units must terminate with units which are not sulfonated end-capping units. These termini will typically be hydroxyl groups or other groups attributable to the unit-forming reactant. For example in the structure b) above, a chain terminal position to which is attached -H forms a hydroxyl group. In other structures which may be constructed, units such as -(0)CC6H4C(0)-0CH3 and -(0)CCδH4C(0)-0H may be found in terminal positions. Anionic End-Capping Units - The end-capping units used in the esters of the present invention are anionic sulfonated groups. These end-cap units provide anionic charged sites when the esters are dispersed in aqueous media, such as a laundry liquor. The end-caps serve to assist transport in aqueous media and to provide hydrophilic sites on the ester molecules. It is not intended to exclude the acid form, but most generally the esters herein are used as sodium salts, as salts of other alkali metals, as salts with nitrogen-containing cations (especially tetraalkylammonium), or as the disassociated ions in an aqueous environment. Examples of anionic end-capping group monomers include sodium isethionate, sodium 2-(2-hydroxyethoxy)ethanesulfonate, sodium 2-[2-(2-hydroxyethoxy)ethoxy]ethanesulfonate, sodium 5-hydroxy-4- methyl-3-oxapentanesulfonate, sodium alpha-3-sulfopropyl-omega- hydroxy-poly(oxy-l,2-ethanediyl), sodium 5-hydroxy-3-oxa-hexanesul- fonate, sodium 3-hydroxy-l-propanesulfonate, sulfobenzoyl and mixtures thereof. Symmetry - It is to be appreciated that in esters in which oxy-l,2-propyleneoxy units are also present, the oxy-l,2-propyl- eneoxy units can have their methyl groups randomly alternating with one of the adjacent -CH2- hydrogen atoms, thereby lowering the symmetry of the ester chain. Thus, the oxy-l,2-propyleneoxy unit can be depicted as having either the -0CH2CH(CH3)0- orientation" or as having the opposite -OCH(CH3)CH2θ- orientation. Carbon atoms in the oxy-l,2-propylene units to which the methyl groups are attached are, furthermore, asymmetric, i.e., chiral; they have four nonequivalent chemical entities attached. Preferably, various optional units of a hydrophilicity- enhancing and nonpolyester substantive type can be incorporated into the esters. The pattern of such incorporation will generally be random. Preferred optional units are anionic hydrophiles, such as 5-sulfoisophthaloyl or similar units. 0 It should also be noted that the essential non-charged aryldicarbonyl units herein need not exclusively be terephthaloyl units. Thus, for example, minor amounts of isomeric non-charged dicarbonyl units, such as isophthaloyl or the like, are acceptable for incorporation into the esters. Method for Making Sulfonated End-Capped Esters - The ester compositions of the present invention can be prepared using any one or combination of several alternative general reaction types, each being well-known in the art. Many different starting materials and diverse, well-known experimental and analytical techniques are 0 useful for the syntheses. Mechanistically, the suitable general reaction types for preparing esters of the invention include those classifiable as: 1. alcoholysis of acyl halides; 2. esterification of organic acids; 5 3. alcoholysis of esters (transesterification); and 4. reaction of alkylene carbonates with organic adds. Of the above, reaction types 2-4 are highly preferred since 0 they render unnecessary the use of expensive solvents and halogenated reactants. Reaction types 2 and 3 are especially preferred as being the most economical. Suitable starting materials or reactants for making the esters of this invention are any reactants (especially esterifiable or ^ transesterifiable reactants) that are capable of combining in accordance with the reaction types 1-4, or combinations thereof, to provide esters having the correct proportions of all the above-specified units (i) to (iv) of the esters. Such reactants can be categorized as "simple" reactants, i.e., those that are singly capable of providing only one kind of unit necessary for making the esters, or as derivatives of the simple reactants which singly contain two or more different types of unit necessary for 5 making the esters. Illustrative of the simple kind of reactant is dimethyl terephthalate which can provide only terephthaloyl units. In contrast, bis(2-hydroxypropyl)-terephthalate is a reactant that can be prepared from dimethyl terephthalate and 1,2-propylene glycol and which can desirably be used to provide two kinds of 10 unit, viz. oxy-l,2-propyleneoxy and terephthaloyl, for making the esters herein. In principle it is also possible to use oligoesters, or polyesters such as poly(ethylene terephthalate), as reactants herein and to conduct transesterification with a view to 15 incorporation of end-capping units while decreasing molecular weight. Nonetheless, the more highly preferred procedure is to make the esters from the simplest reactants in a process involving molecular weight increase (to the limited extent provided for by the invention) and end-capping. 20 Since "simple" reactants are those which will most preferably and conveniently be used, it is useful to illustrate this kind of reactant in more detail. Thus, 2-(2-hydroxyethoxy)ethanesulfonate can be used as the source of the end-capping units herein. Note that the metal cation can be replaced by potassium or a nitrogen- R " containing cation provided that the latter does not overly promote crystallization of the oligomer and is unreactive during the synthesis, e.g. tetraalkylammonium. It is, of course, possible to subject any of the esters of the invention to cation exchange after the synthesis and, thereby, afford a means of introducing more 30 esoteric or reactive cations into the ester compositions. Appropriate glycols or cyclic carbonate derivatives thereof can be used to provide oxy-l,2-alkyleneoxy units; thus, 1,2-propylene glycol or (where the starting carboxyl groups are present in an acidic form) the cyclic carbonate are suitable sources of oxy-l,2-propyleneoxy units for use herein. Oxyethyleneoxy units are most conveniently provided by ethylene glycol. Although, as an alternative, ethylene carbonate could be used when free carboxylic acid groups are to be esterified. Aryldicarboxylic acids or their lower alkyl esters can be used to provide the essential aryldicarbonyl units; thus, terephthalic acid or dimethyl terephthalate are suitable sources of terephthal¬ oyl units. In general, it is preferred herein to use ester rather than acid forms of reactants to provide the aryldicarbonyl units. Other units of the esters will be provided by well-known and readily identifiable reagents; for example, dimethyl 5-sulfoiso- phthalate is an example of a reagent capable of providing 5-sulfo- isophthaloyl units for optional incorporation into the esters of the invention. It is generally preferred that all units of the type (iv) as defined hereinabove should be provided by reactants in ester or carboxylic acid forms. When starting with the simplest reactants as illustrated above, the overall synthesis is usually multi-step and involves at least two stages, such as an initial esterification or trans- esterification (also known as ester interchange) stage followed by an o igomerization stage in which molecular weights of the esters are increased, but only to a limited extent as provided for by the invention. Formation of ester-bonds in reaction types 2 and 3 involves elimination of low molecular weight by-products such as water (reaction 2) or simple alcohols (reaction 3). Complete removal of the latter from reaction mixtures is generally somewhat easier than removal of the former. However, since the ester-bond forming reactions are generally reversible, it is necessary to "drive" the reactions forward in both instances by removing these by-products. In practical terms, in the first stage (ester interchange) the reactants are mixed in appropriate proportions and are heated to provide a melt at atmospheric or slightly superatmospheric pressures (preferably of an inert gas such as nitrogen, or argon). Water and/or low molecular weight alcohol is liberated and is distilled from the reactor at temperatures up to about 200°C. (A temperature range of from about 150-200°C is generally preferred for this stage). In the second (i.e., oligomerization) stage, vacuum and temperatures somewhat higher than in the first stage are applied; removal of volatile by-products and excess reactants continues until the reaction is at the desired stage of completion, as monitored by conventional spectroscopic techniques. Continuously applied vacuum, typically of about 50 mm Hg or lower can be used. In both of the above-described reaction stages, it is neces¬ sary to balance on one hand the desire for rapid reaction (higher temperatures and shorter times preferred), against the need to avoid thermal degradation (which undesirably might result in off-colors and by-products). It is possible to use generally higher reaction temperatures especially when reactor design minimizes super-heating or "hot spots"; also, ester-forming reactions in which ethylene glycol is present are more tolerant of higher temperatures. Thus, a suitable temperature for oligomerization lies most preferably in the range of from about 150°C to about 260°C when higher ratios of EG/PG are present and in the range of from about 150°C to about 240°C when lower ratios of EG/PG are present (assuming that no special precautions, such as of reactor design, are otherwise taken to limit thermolysis). When tetraalkylammonium cations are present, condensation temperatures are preferably 150-240°C. It is very important in the above-described procedure to use continuous mixing so that the reactants are always in good contact; highly preferred procedures involve formation of a well-stirred homogeneous melt of the reactants in the temperature ranges given above. It is also highly preferred to maximize the surface area of reaction mixture which is exposed to vacuum or inert gas to facilitate the removal of volatiles, especially in the oligomeri¬ zation step; mixing equipment of a high-shear vortex-forming type giving good gas-liquid contact are best suited for this purpose. Catalysts and catalyst levels appropriate for esterification, transesterification, oligomerization, and for combinations thereof are all well-known in polyester chemistry, and will generally be used herein; as noted above, a single catalyst will suffice. Suitably catalytic metals are reported in Chemical Abstracts, CA83:178505v, which states that the catalytic activity of transition metal ions during direct esterification of K and Na carboxybenzenesulfonates by ethylene glycol decreases in the order Sn (best), Ti, Pb, Zn, Mn, Co (worst). The reactions can be continued over periods of time sufficient to reach the desired level of oligomerization, or various conventional analytical monitoring techniques can be employed to monitor progress of the forward reaction. Such monitoring makes it possible to speed up the procedures somewhat and to stop the reaction as soon as a product having the minimum acceptable composition is formed. In general when tetraalkylammonium cations 0 are present, is is preferred to stop the reaction at less than full completion, relative to the sodium cation form, to reduce the possibility of thermal instability. Appropriate monitoring techniques include measurement of relative and intrinsic viscosities, hydroxyl numbers, H and ^ 3 C 5 nuclear magnetic resonance (n.m.r) spectra, and liquid chroma- tograms. Most conveniently, when using a combination of volatile reactants (such as a glycol) and relatively involatile reactants (such as dimethyl terephthalate), the reaction will be initiated ° with excess glycol being present. As in the case of ester interchange reactions reported by Odian (op. cit.), "stoichiometric balance is inherently achieved in the last stages of the second step of the process". Excess glycol can be removed from the reaction mixture by distillation; thus, the exact amount used is 5 not critical. Inasmuch as the final stoichiometry of the ester compositions depends on the relative proportions of reactants retained in the reaction mixtures and incorporated into the esters, it is desirable to conduct the condensations in a way which effectively retains the 0 non-glycol eactants and prevents them from distilling or subliming. Dimethyl terephthalate and to a lesser extent the simple glycol esters of terephthalic acid have sufficient volatility to show on occasion "sublimation" to cooler parts of the reaction apparatus. To ensure achieving the desired stoichiometry, ^ it is desirable that this sublimate be returned to the reaction mixture or, alternatively, that sublimation losses be compensated by use of a small excess of terephthalate. In general, sublimation-type losses, such as of dimethyl terephthalate, may be minimized 1) by apparatus design; 2) by raising the reaction temperature slowly enough to allow a large proportion of dimethyl terephthalate to be converted to less volatile glycol esters before reaching the upper reaction temperatures; 3) by conducting the early phase of the transesterification under low to moderate pressure (especially effective is a procedure allowing sufficient reaction time to evolve at least about 90% of the theoretical yield of methanol before applying vacuum). On the other hand, the "volatile" glycol components used herein must be truly volatile if an excess is to be used. In general, lower glycols or mixtures thereof having boiling points below about 350°C at atmospheric pressure are used herein; these are volatile enough to be practically removable under typical reaction conditions. Typically herein, when calculating the relative molar pro¬ portions and the target Completion Index for a polymer synthesis, the following routine is followed as illustrated for a combination of reactants sodium 2-(2hydroxyethoxy)ethanesulfonate (A), ethylene glycol (B), propylene glycol (C), dimethyl terephthalate (D), and dimethyl 5-sulfoisophthalate (E): 1. The generalized target structure is selected for a fully dicapped polymer consisting of units derived from the desired monomeric reactants. In this example, the generalized target structure is: (CAP)2(EG/PG) x (T) y (SI) z , where the CAP units are derived from (A), the EG/PG units from (B) and (C), the T units from (D), and the SI units from (E); 2. The average number of terephthalate units desired for the target structure is selected; for the present example, the value of 5 is selected for y, which falls in the range of most highly preferred values according to the invention, is used; 3. The average number of " sulfoisophthalate units desired for the target structure is selected; for the present example, the value of 1 is selected for z, which falls in the range of the most highly preferred values according to the invention, is used; 4. The mole ratio of (A) to (D) to (E) should thus be 2:5:1; amounts of the reactants (A), (D), and (E) are taken accordingly; 5. An appropriate excess of the glycols is selected; typically 2 to 10 times the sum of the number of moles of dimethyl terephthalate plus dimethyl 5-sulfoisophthalate is suitable; in this example, the glycols are ethylene glycol, (B) and propylene glycol, (C); 5 6. The target ratio of incorporated ethylene glycol :propylene glycol (EG/PG ratio is selected; for the present example, the ratio of 2:1 is selected which is in the most highly preferred range according to the invention; typically, the EG/PG ratio incorporated is higher than the initial (B):(C) reactant ratio 10 because of volatility and reactivity differences; for this reason the initial (B):(C) ratio of about 1.5:1 is selected for this example to give a 2:1 EG/PG ratio in the final oliogomer. 7. The target Completion Index is calculated which will 1 correspond to the desired molecular weight range for the desired, partially polymerized ester; this calculation is based on the simplifying assumptions: first that the 13 C-NMR peak heights accurately reflect the ratios of the different kinds of species present and second, that although the 20 measurements are made only for ethylene glycol esters, the same ratio of di:monoesters exists for both ethylene and propylene glycols. The calculation is also based on a formalism in which a fully polymerized sample is reacted with glycol by transesterification such that one free glycol reacts " with one diester of glycol in the polymer to produce two monoesters of glycol as end groups of polymer fragments. The number of such cleavages needed to reduce the average molecular weight to the desired range is then determined and the ratio of glycol diesters:monoesters at that degree of 30 cleavage is determined. From this, the ratio of 1 3 C-NMR peaks for monoester and diesters of ethylene glycol at the desired level of cleavage is determined and converted to a Completion Index. For simplicity, the cleavages are assumed to occur only at glycol diester linkages and the contribution of 35 attacking glycol to the molecular weight of the cleaved polymer is ignored. For the present example, the calculation is as follows: a. Average MW of fully polymerized target 1594 b. Average MW for desired ester 640 c. Fraction of target MW desired (640/1594) 1/2.5 d. # of cleavages necessary by glycol transesterifications to get average MW reduced by 1/2.5 1.5 e. Moles of glycol to cleave target 1.5 times 1.5 f. Moles of glycol in average, fully polymerized target 5 g. Total moles glycol after 1.5 cleavages 6.5 h. Monoesters of glycol after 1.5 cleavages 3 i- Diesters of glycol after 1.5 cleavages 3.5 13 j . Diester carbons at -63 ppm in C-NMR after 1.5 cleavages (3.5 diesters X 2 carbons per ester) 7 (assuming all ethylene glycol) k. Monoester carbons at -60 ppm in 13 C-NMR after 1.5 cleavages (3 monoesters X 1 carbon per ester) 3 (assuming all ethylene glycol) 1. Calculated 63/60 peak height ratio (7/3) 2.3 m. Calculated Cαπpletion Index far desired ester 2.3 Oliganeric esters useful as dispersing agents as disclosed in this invention may also be prepared from an oligomeric ester conprising the desired monomer units but with a higher Completion ndex than desired. The oligomeric ester is mixed with ethylene glycol, or a mixture of ethylene glycol and propylene glycol, under heat to reverse the polymerization of the oligomer. The glycol acts to cleave the oligomer and, thereby, provides a mixture of oliganeric esters with a lower average Completion Index. Preferably, if a mixture of ethylene glycol and propylene glycol is used, the ratio of ethylene glycol to propylene glycol will be about the same as the ratio of the two glycols present in the oligomeric ester. The amount of glycol to be mixed with the oligomeric ester is dependant upon the final Completion Index desired. Generally, a lower Completion Index will be achieved by using more glycol. Dispersing agents which contain end-cap units having from 1 to 3 ethylene or propylene groups and a ratio of oxyethyleneoxy to oxy-l,2-propyleneoxy units of above about 0.5:1, may undergo undesirable crystallization during synthesis or when introduced to the laundry liquor. A sulfonate-type hydrotrope or stabilizer, such as alkylbenzenesulfαnate, cumenesulfonate or toluenesulfonate, may be mixed with the reactants during synthesis of the ester to reduce the crystallization problem. Typically 0.5% to about 20%, by weight of the ester composition, of stabilizer is added to the opposition. In light of the teaching of the present invention (insofar as the identity and proportions of end-capping and backbone units are concerned) , numerous syntheses of ester compositions according to the invention follow straightforwardly from the above disclosure. The following, more detailed examples are illustrative. EXAMPLE I Synthesis of Sodium 2-(2-hydroxyethoxy)ethanesulfαnate A 1 liter, 3-neck, round-bottαn flask equipped with magnetic TM stirring bar, pH probe, thermometer attached to a Therm-O-Watch (I K) , and an inert gas inlet through a condenser is charged with 400g of distilled water. This is deoxygenated by bubbling inert gas through the water far 30 minutes while stirring vigorously. To this is added sodium hydroxide (40.0g, 1.00 mol, Mallinckrodt) . When the solution is homogeneous, a glass tube is placed into the solution through a Clasien head while maintaining the inert atmosphere in the system. The pH is above 11. Sulfur dioxide gas (Air Products Co.) is bubbled into the basic solution at ca. 0.02 mol per minute. When the pH of the solution drops to 4.0 in ca. 1 hr, the SO- addition is stopped. The temperature of the solution is raised to ca. 85 C and held there. Inert gas is used to flush the delivery tube free of residual SO_. Ethylene oxide (Wright Brothers Corp.) is then bubbled through the hot, pale yellow aqueous solution at a rate of ca. 0.02-0.03 mol per minute. Conversion of the sulfite to isethionate is monitored by iodometric titratiαn of 0.50ml aliquots of the reaction. The pH of the solution slowly rises as the sulfite reacts. Only after ca. 98% of the sulfite is consumed does the reaction mixture become mildly alkaline. At the very end, when the titration indicates that essentially no sulfite remains, the pH rises to 9. At this point, the addition of ethylene oxide is stopped. The pH of the clear solution is adjusted back down to ca. pH 5 by the addition of a small amount of 5M sulfuric acid. This adjustment of pH is repeated as needed until the pH stabilizes (usually after a few minutes) . At this point any tiny residual of sulfite may be discharged by adding a corresponding amount of 30% H_0 to oxidize it to sulfate. (Alternatively, any sulfite residual may be oxidiz¬ ed after conversion to sodium 2-(2-hydroxyethoxy)-ethanesulfonate.) The resulting isethiαnate solution may be used directly for conver¬ sion to modified isethionates. Conversion of the isethiαnate solution into sodium 2-(2-hydrαxyBthoκy)ethanesulfαnate is accomplished by adding sodium hydroxide (4.00g, 0.10 mol, Mallirkckrodt) and ethylene glycol (260g, 5.9 mol. Baker Chemical Co.). While maintaining the inert atmosphere, the pH probe is removed and replaced by a modified Claisen head to distill out the water. The temperature is gradually raised to ca. 195°C as water distills and then is held for ca. 20 hr as additional water of reaction distills out. The reaction mixture is neutralized to pH 7 with methanesulfαnic acid. This yields 407.9g of stock solution which partially crystallizes at room temperature. This may be used directly for oligomer preparations or if it is desired to isolate the 2-(2-hydroxy- ethαxy)ethanesulfonate, a trace of monobasic potassium phosphate (approximately 1 mole % of the 2-(2-hydrαxyethoxy-ethanesulfαnate salt) is added as a buffer and the excess ethylene glycol is stripped off on a Kugelrohr apparatus under vacuum. The synthesis of modified isethiαnate, particularly αxyalkylated isethiαnate, is preferably conducted with an excess of polyol reactant to isethi nate. A mole ratio of at least 2:1 polyol to isethionate is preferred. In still other more preferred embodiments, a mole ratio of at least 5:1, most preferred from about 5:1 to about 10:1, is used. Even higher ratios of polyol to isethionate can be used to insure predominate mono sulfonate product. Without wishing to be limited by theory, it is believed that the excess polyol reactant provides the desired mono sulfonate product. Use of a 1:1 or lower ratio may lead to predominately disulfαnate product. The preferred polyols include volatile diols, triols, and mixtures thereof, including ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentane- diol, 1,6-hexanediol, 2,2-dimethyl-l,3-propanediol, 2-methyl-l,3- propanediol,glycerin, diethylene glycol, triethylene glycol, and mixtures thereof. The reaction may be conducted at any pressure, typically from about atmospheric to about 300 psig. The temperature of the reaction should be below the temperature in which the polyol will distill off under the reaction conditions, and hi<gh enough to allow removal of the water formed, typically from about 150°c to about 250°C. The reaction is preferably conducted in the presence of a base catalyst. The base is present in an amount equal to from about 1 to about 25 mole percent of the isethionate reactant. In place of the base catalyst, one or more of the hydroxyl subεtituents of the polyol can be converted into an alkoxide. Suitable reactants useful to farm the alkoxide of the polyol include alkali metals, alkali oxides, .alkali hydroxides. Particlularly prefered reactants include sodium metal and sodium hydroxide. The completion of the reaction is dependent on the base used and the temperature at which the reaction is conducted. Typically the reaction is run until most of the theoretical water is dis¬ tilled from the reaction vessel. If a mixture of iethiαnate and modified isethionate is desired, the reaction can be conducted until the desired fraction of theoretical modified isethionate is produced. This can be estimated based on the fraction of theoretical water distilled from the reaction vessel. Additionally, if it is desired to isolate the modified isethionate compound, the excess polyol should preferably be volatile to aid in its removal. Prior to removal of excess polyol by volatilization, it is preferable to neutralize the basic catalyst so that the pH of the system during the stripping be maintained near neutrality. To this end, it is often helpful to add a low level of a buffer, such as an alkali phosphate, to the system. Removal of excess polyol is preferably conducted under a vacuum of less than about 100 mm Hg. Example II Synthesis of Sodium 2-(4-Hyάroxybutoxy)ethanesulfonate Using a Stainless Steel Kettle A 1L stainless steel kettle is fitted with a three neck glass cover which is clamped in place. Through one neck of the lid is inserted a glass rod with a teflon stir paddle at one end. The glass rod is connected to a motor for stirring purposes. The other necks of the lid are equipped with a thermocouple and temperature control device (Therm-0-Watch I2R) , and a modified Claisen head and condenser set for distillation. To this reaction flask is added the isethionic acid, sodium salt (Aldrich, 50.2g, 0.339 moles) and an equal weight of water. The mixture is allowed to stir until the isethionic acid, sodium salt is fully dissolved. One drop of hydrogen peroxide (Aldrich, 30 wt% solution in water, to oxidize any traces of sulfite) is added to the reaction solution, and the solution is allowed to stir for about one hour. At this time the solution tests weakly positive for the presence of peroxide with an indicator strip. The 1,4-butanediol (Aldrich, 213.6g, 2.37 moles) and the sodium hydroxide (Mallinkrodt, 1.36g, 0.034 moles) are added to the flask. The reaction is heated at 225 C under an argon environment for 4 hours as water distills from the reaction vessel. The temperature of the viscous product mixture is lowered to 90°C. At this temperature, the pH of the solution is adjusted to neutral with methanesulfonic acid (Aldrich) . The product mixture is new dissolved in deionized water to farm a 30% solution. The solution is transferred to a 1L, single neck, round bottom flask. To the flask is added a small amount of potassium phosphate, monobasic (Aldrich, 2.6g, 0.019 moles, 6 mole% relative to amount of isethionic acid, sodium salt) in order to protect against pH shifts during the stripping operation. At this point, the pH of the soution measures -5.5. The pH is readjusted to 7 using IN NaOH solution and a pH meter. The majority of the water is stripped on the Rotavapor (Buchi) under aspirator vacuum at 65°C. Next, the flask is placed in a Kugelrohr apparatus (Aldrich) under a 2mm Hg vacuum. The temperature of the Kugelrohr is maintained at 170°C for 1.5 hours to remove the excess 1,4-butanediol and the last traces of water. The product is a light yellow, brittle solid. 13 A C-NMR (in D_0) shows characteristic resonances at -25 ppm (-α^α^αH), -28 ppm (-cα^c^α^α^oH), -soppm (Nas ^-), -61.5 (NaSO-CH-CH-O-) . Likewise, a -1.7 ppm for 4 protons (-o ^α^σ^^OH) , -3.3 ppm for 2 protons (NaSO. j α j -), -3.7 ppm for 4 protons , and -3.9 ppm for 2 protons (NaSO-CH-CH-O-) . Integrals are consistent with the complete removal of excess butanediol. EXAMPLE III An ester σcπposition made from sodium 2-(2-hydroxyethoxy)- etnanesulfonate, monosodium salt, ethylene glycol, 1,2-propylene glycol, and dimethyl terephthalate. The exaπple illustrates an ester composition according to the invention wherein the backbone contains a mixture of essential ethylene glycol and nonessential 1,2-propylene glycol. A 1L, three neck, round bottom flask is equipped with a magnetic stir bar, a modified Claisen head, a thermometer, a temperature control device (Therm-O-Watch , IT*) , and a condenser set for distillation. To the reaction flask are added the reagents sodium 2-(2-hvdrαxyethαxy)ethanesulfonate (prepared as in Example I, 40.lg, 0.209 moles), dimethyl terephthalate (Aldrich, 80.8g, 0.416 moles), ethylene glycol (Baker, 105.Og, 1.69 moles), propylene glycol (Baker, 120.3g, 1.58 moles), and catalyst titanium (IV) pαrpαxide (Aldrich, 0.058g, 0.02% of total reaction weight). Also added are the hydrotropes sodium cumenesulfonate, sodium toluenesulfonate, and sodium xylenesulfonate (all from Ruetgers- Nease, 4.8g each, each is 4% of final polymer weight). The reaction mixture is heated at a constant temperature of 180°C under an argon environment for a period of one day as methanol and water distill frcm the reaction vessel to give a prepolymer reaction product. An 81.7g portion of this prepolymer solution is poured in a 1L, single neck, round bottom flask and placed in a Kugelrohr apparatus (Aldrich) under a 2 mmHg vacuum. The temperature of the Kugelrohr is raised to 240°C and maintained at this temperature for 6 minutes. At this time, the heating element is switched off, and the flask is allowed to cool to room temperature under continuous vacuum for thirty minutes. The yield of the desired oligomer is 13 37.6g of opaque, light yellcw glassy material. A C-NMR (in EMSO-d ) shews a resonance for diesters of ethylene glycol (-C(0)C H 2 CH 2 OC(0)-) at -63.2 ppm, and a resonance for monoesters of ethylene glycol at -59.2 ppm. The ratio of the height of the diester peak to the height of the monoester peak is found to be 2.8:1.0 for a Completion Index (CI) of 2.8. A Ti-NMR (in EMSO-dg) shows a resonance at -7.9 ppm for the aromatic protons in the terephthalate groups, and a resonance at -2.8 ppm for the proton adjacent to the sulfur (-CH-SO Na) in the capping groups derived from 2-(2-hydroxyethαxy)ethane-sulfαnate. The ratio of the area of the peak for protons in the methylene group of diesters of ethylene glycol at -4.7 ppm to the area of peak for the methyne proton of diesters of propylene glycol at -5.4 ppm is measured. From this, the molar ratio of incorporated ethylene/propylene glycols (EG/PG ratio) is calculated to be 1.6. A small sample of the finished polymer is placed into a screw cap vial, and crushed into fine particles. Enough deionized water is added to make 2% solution by weight. The polymer initially dissolves to form a clear solution, but becomes a cloudy, milky white color over the course of two hours. EXAMPLE TV An ester composition made from m-sulfobenzoic acid, monosodium salt, ethylene glycol, propylene glycol, dimethyl 5-sulfoisophtha¬ late, sodium salt, and dimethyl terephthalate. The example illus¬ trates an ester composition according to the invention wherein the ester molecules have a backbone incorporating sulfonated units. To a 1L, three neck, round bottom flask equipped with a magnetic stirring bar, modified Claisen head, condenser (set for distillation) , thermometer, and temperature controller (Therm-O-Watch , IT*) is added m-sulfobenzoic acid, monosodium salt (50.0g, 0.223 mol), dimethyl terephthalate (237.9g, 1.22 mol), dimethyl 5-sulfoisophthalate, sodium salt (Aldrich, 66.Og, 0.223 mol), ethylene glycol (Baker, 103.7g, 1.67 mol), propylene glycol (Fisher, 127.lg, 1.67 mol), titanium (IV) propoxide (Aldrich, 0.10g, 0.02% of total reaction wei t) , sodium acetate (Baker, 0.73g, 2 mol% of dimethyl 5-sulfoisophthalate, sodium salt and m-sulfobenzoic acid, monosodium salt) , sodium cumenesulfonate (Ruetgers-Nease, 14g, 4% of final polymer wt.), sodium xylenesulfonate (Ruetgers-Nease, 14g, 4% of final polymer wt.) and sodium toluenesulfonate (Ruetgers-Nease, 14g,4% of final polymer wt.) . This mixture is heated to 180°C and maintained at that temperature for 2 nights under argon as methanol and water distill from the reaction vessel. A -224g portion of the material (prepolymer) is transferred to a IL, single neck, round bottom flask and heated gradually over about 20 minutes to 240°C in a Kugelrohr apparatus (Aldrich) at about 2mm Hg and maintained there for 10 min. The reaction flask is then allowed to air cool quite rapidly to near room temperature under vacuum (-30 min.) The reaction affords 139g of the desired oligomer as a yellow crunchy glass. A 13 C-NMR(DMSO-d 6 ) shows a resonance for - fOJCOL^O^OfOJC- at -63.2 ppm (diester) and a resonance for -CfOJCCH-OLOH at 59.4 ppm (mαnoester) . The ratio of the diester peak to the mαnoester peak is measured to be 1.4:1.0 for a Completion Index [C.l. (63/60) ] of 1.4. A Ti-NMR(DMSO-dg) shews a resonance at -8.4 ppm representing the sulfoisophthalate aromatic hydrogens, a resonance at -8.3 ppm representing one of the sulfobenzoate aromatic hydrogens, and a resonance at -7.9 ppm representing terephthalate aromatic hydrogens. The ratio of the peak for the methylene groups of diesters of ethylene glycol at -4.7 ppm to the area of the peak for the methyne proton of diesters of propylene glycol at -5.4 ppm is measured, from this, the molar ratio of incorporated ethylene/ propylene glycols (EG/PG ratio) is calculated to be 1.5:1. The solubility is tested by weighting a small amount of material into a vial, adding enough distilled water to make a 35% by wei t solution, and agitating the vial vigorously. The material is mostly soluble under these conditions. The milky solution which forms gels after a few hours. Heating a 194g sample of the above prepolymer on a Kugelrohr apparatus at 240°C for 20 min. at 2mm Hg, affords 150g of yellow crunchy glass with an EG/PG = 1.4 and CI(63/60) = 2.3. This material is soluble under the above conditions. It makes a clear solution which becomes cloudy after approximately 1 day. Approximately lOOg of each of the above oligomers is retained. The remaining material is combined in a IL round bottom flask and heated an a Kugelrohr apparatus at 240°C for 15 min. at -2mm Hg to afford 67.2g of yellow crunchy glass with an EΞ/PG = 1.4 and CI(63/60) = 4.9. This material is soluble under the above conditions. It makes a clear solution which becomes cloudy after approximately 3 days. The oligomers representing a Ccπpletion Index range of 1.4 to 4.9 are used directly as soil suspension agents. EXAMPLE V An ester composition made from m-sulfobenzoic acid monosodium salt, ethylene glycol, dimethyl 5-sulfoisophthalate, sodium salt, and dimethyl terephthalate. The example illustrates an ester cαmposition according to the invention with low completion index. To a 250ml, three neck, round bottom flask equipped with a magnetic stirring bar, modified Claisen head, condenser (set for distillation) , thermometer, and temperature controller (Therm-O-Watch , IT*) is added 3-sulfobenzoic acid, monosodium salt (Eastman Kodak, 30.3g, 0.135 mol), dimethyl terephthalate (Aldrich, 65.6g, 0.338 mol), dimethyl 5-sulfoisophthalate, sodium salt (Aldrich, 20.Og, 0.0675 mol), ethylene glycol (Baker, 41.9g, 0.675 mol), hydrated monobutyltin oxide (M&T Chemicals, 0.32g, 0.2% of total reaction weight), and sodium acetate (MCB, 0.33g, 2 mol% of sum of sulfobenzoic acid, monosodium salt and dimethyl 5-sulfoisophthalate, sodium salt) . This mixture is heated to 180°C and maintained at that temperature overnight under argon as 13 methanol and water distill form the reaction vessel. A C-NMR taken at the reaction mixture at this point shows some residual methyl ester. About 20g more ethylene glycol is added and heating is continued far another 18 hours to give a material with no detectable residual methyl ester. The material is transferred to a 1000ml, single neck, round bottom flask and heated gradually over about 20 minutes to 240°C in a Kugelrohr apparatus (Aldrich) at about 0.5mm Hg and maintained there for 2.5 hours. The reaction flask is then allowed to air cool quite rapidly to near room temperature under vacuum (-30 min.) The reaction affords about llOg of the desired oligomer as an orange glass. A 13 C-NMR(OlS0-d 6 ) shows a resonance for -C(0) 0Ckl tl 2 0(0) C- at -63.2 ppm (diester) and a resonance for at -59.4 ppm (monoester) . The ratio of the heights of the diester to monoester peaks is measured to be 6.8:1 for a Corpletion Index of 6.8. A H-NMR(CMSO-d 6 ) shews a resonance at -8.4 ppm representing the sulfoisσphthalate aromatic hydrogens and a resonance at -7.9 ppm representing terephthalate aromatic hydrogens. The solubility is tested by weighing small amounts of material into 2 vials, crushing it, adding enough distilled water to make 5% and 10% by weight solutions, and agitating the vials vigorously. The material dissolves under these conditions. EXAMPLE VT An ester composition made from sodium 2-(2-hydroxyethoxy)- ethanesulfαnate, dimethyl terephthalate, dimethyl 5-sulfoiso¬ phthalate, sodium salt, ethylene glycol, and propylene glycol with mixed hydrσtrope stabilizer. The example illustrates an ester composition according to the invention with a lew Corpletion Index. A IL, three neck, round bottom flask is equipped with a magnetic stir bar, a modified Claisen head, a thermometer, a TM 2 temperature controller (Therm-O-Watch , I R) , and a condenser set for distillation. To this reaction flask is added the sodium 2-(2-hydrctχyethαxy)ethanesulfonate (prepared as in Example I), 75.Og, 0.390 moles), dimethyl terephthalate (Aldrich, 189.3g, 0.975 moles), dimethyl 5-sulfoisophthalate, sodium salt, (Aldrich, 57.8g, 0.195 moles), ethylene glycol (Baker, 193.7g, 3.12 moles), and propylene glycol (Baker, 237. g, 3.12 moles). Also added is sodium acetate (Baker, 0.320g, 2 mole% of dimethyl 5-sulfoisophthalate, sodium salt) , catalyst titanium(TV) propoxide (Aldrich, 0.126g, 0.02% of total reaction weight), and hydrσtropes sodium cumenesul- fonate, sodium toluenesulfonate, and sodium xylenesulfonate (all from Ruetgers-Nease, 12.9 g each, each is 4% of final polymer weight) . The reaction mixture is heated at a constant 180 C under an argon environment for a period of two days as methanol and water distill from the reaction vessel to give a prepolymer reaction product. At this time, an 80.5g portion of the prepolymer solution is poured into a IL, single neck, round bottom flask and placed in a Kugelrohr apparatus (Aldrich) under a 2mm Hg vacuum. The temperature of the Kugelrohr is raised to 240°C and maintained for 20 minutes. The heating element is switched off, and the flask containing the polymer is allowed to cool under continuous vacuum for thirty minutes. The yield of the desired oligomer is 36.6g of translucent, light yellow, glassy material . A 13 C-NMR (in DMSO-d 6 shews a resonance for diesters of ethylene glycol (-C(0)QCH 2 CH 2 OC(0)-) at -63.2 ppm, and a resonance for monesters of ethylene glycol at -59.2 ppm. The ratio of the height of the diester peak to the height of the monoester peak is found to be 3.9:1 for a Completion Index (CI) of 3.9. A Ti-NMR (in DMSO-dg) shews a resonance at -8.4 ppm for the aromatic protons in the sulfoisophthalate group, a resonance at -7.9 ppm for the aromatic protons in the terephthalate groups, and a resonance at -2.8 ppm for the protons adjacent to the sulfur (-OLSO-Na) in the capping groups derived frαn the sodium 2-(2-hvdroκyethαxy)ethanesulfσnate. The ratio of the area of the peak for protons in the methylene group of diesters of ethylene glycol at -4.7 ppm to the area of the peak for the methyne proton of diesters of propylene glycol at -5.4 ppm is measured and fund to be 1.7:1. From this, the molar ratio of incorporated ethylene/pro- pylene glycols (EG/PG ratio) is calculated to be 1.7. A small sample of the finished polymer is placed into a screw cap, glass vial for solubility testing. It is crushed, and enough deionized water is added to make a 35% solution by weight. The polymer initially dissolves to form a clear solution, but after 3 hours the solution is milky white in color. The solution gels after two days. A second portion of the prepolymer (80.5g) is added to a IL, single neck, round bottom flask and is placed on the Kugelrohr under vacuum as above. However, this proton is heated for only five minutes at 240°C. The NMR spectrum taken of the resulting polymer in DMSO-dg yields " CI = 1.3 and EG/PG = -1.7 by the same methods described above. An 18.5g portion of this polymer is added to a 500mL, single neck, round bottom flask and is placed back on the Kugelrohr apparatus under vacuum. Again, the temperature of the Kugelrohr is allowed to rise to 240°C, and is maintained at this temperature for only 30 seconds. The NMR spectrum at this point reveals the CI = 2.0 and EG/PG = -1.7. The yield of this desired polymer is 17.5g of translucent, light yellow, glassy material. A 35% by wei t solution of this polymer is made up in deionized water. The solution is initially clear, but becomes cloudy within an hour, and gels within 5 hours. A third portion of prepolymer (81.3g) is added to a IL, single neck, round bottcm flask, and is heated under the same temperature and pressure conditions as above. The 240°C temperature is maintained for 3 minutes and 30 seconds. The NMR spectroscopy data gives CI = 1.4 and EG/PG = -1.7. Part of this polymer (17.lg) is put into a 500mL, single neck, round bottom flask and heated on the Kugelrohr under the same conditions as described above. The 240°C temperature is maintained for 1 minute. The spectral data gives a a = 2.3 and EG/PG » -1.7. The yield of this polymer is 16.4g of translucent, light yellow, glassy material. A 35% by weight solution of this polymer is made up in deionized water in the same manner as with the previous polymers. The solution is initially clear, but turns cloudy after 1 hour, and gels between 6 and 24 hours. The samples which cover a range of Completion Indices between 1.3 and 3.9 are used directly as soil suspension agents. Test Method The extent of oligomerization can be estimated from the Completion Index which is proportional to the diester:monoester ratio for ethylene glycols incorporated into the oligomeric structure. An oligomer with a low Completion Index will have a relatively low proportion of diesters of ethylene glycol and therefore have a low degree of oligomerization. An oligomer with a high Ccπpletiαn Index will have a relatively high proportion of diesters of ethylene glycol and therefore have a high degree of oligomerization. As a theoretical limit, a fully dicapped oligomer will have all diesters and no monoesters of ethylene glycol and will have an infinite Completion Index. The following test method can be used to determine the "Oαspletiαn Index" of the dispersing agents of the invention. 1. The dispersing agent is well mixed as a melt to ensure representative sampling and is cooled rapidly from a temperature above the melting-point to well below the vitrification temperature, e.g., 45°C or lower. 2. A solid sample of the bulk dispersing agent is taken. 3. A 10% solution of the dispersing agent in (methyl sulfoxide)-d, containing 1% v/v tetramethylsilane o (Aldrich Chemical Co.) is made up. If necessary, warming to 90-100 C is used to achieve substantially complete dissolution of the dispersing agent. 4. The solution is placed in a 180X5 mm NMR tube (Wilmad Scientific Glass, 507-pp-7 Royal Imperial thin-walled 5mm NMR sample tubes, 8".) 13 5. The C NMR spectrum is obtained under the following conditions: a. General Electric QE-300 NMR instrument b. probe temperature = 25°C c. one pulse sequence d. pulse width = 6.00 microseconds = 30 degree e. acquisition time = 819.20 msec f. recycle time = 1.00 sec g. no. of acquisitions = 5000 h. data size = 32768 i. line broadening = 3.00 Hz j. spin rate = 13 rps k. observe: frequency = 75.480824 MHz spec width = 20,000 Hz gain = 60*8 1. decoupler: standard broad band, 64 modulation frequency = 4.000 ppm power = 2785/3000 m. plot scale: 510.64 " Hz/cm 6.7652 ppm/cm from 225.00 to -4.99 ppm 6. The height of the tallest resonance observed in the 63.0-63.8 ppm region (referred to as "the 63 peak" and associated with diesters of ethylene glycol) is measured. (This is often observed as a single peak under the specified conditions but may appear as a poorly resolved multiplet) . 7. The height of the tallest resonance observed in the 59-59.7 ppm region (referred to as "the 60 peak") and associated with monoesters of ethylene glycol is measured. (When this is large enough to distinguish from the baseline, it normally appears to be a single peak under the specified conditions.) 8. The Completion Index is calculated as the height ratio for the "63 peak" over the "60 peak". In the special case where the dispersing agent comprises oxy-l,2-oxvpropyleneoxy units but very little or no oxyethyleneoxy units, the measurement of Ccπpletion Index based on di- and monoesters of ethylene glycol is not feasible. In these cases, the Completion Index can be estimated by using proton NMR (p r) resonances for propylene glycol diesters (at about 1.4 ppm) and for propylene glycol monoesters (in the range of about 1.1 to 1.3 ppm) . These resonances are integrated, and the ratio taken. The resulting ratio is then multiplied by a factor of 2 to convert it to the same basis as the Completion Index derived from carbon NMR resonances. This may be expressed as the equation: (pmr peak area at 1.4 ppm) (2)/(pmr peak area at 1.1-1.3 ppm) = Completion Index. Use of Dispersing Agents in Detergent campositions - Esters of the invention are especially useful as dispersing agents of a type compatible in the laundry with conventional detersive ingredients such as those typically found in liquid detergents, granular laundry detergents or laundry bars. Additionally, the esters are useful in laundry additive or pretreatment compositions comprising the essential ester compositions and conventional detergent ingredients. U.S. Patent 3,178,370, Qkenfuss, issued Apr. 13, 1965, describes laundry detergent bars and processes for making them. Philippine Patent 13,778, Anderson, issued Sept. 23, 1980, describes synthetic detergent laundry bars. Methods for making laundry detergent bars by various extrustion processes are well known in the art. Detersive Surfactant - The amount of detersive surfactant included in the fully-formulated detergent compositions afforded by the present invention can vary from about 1% to about 99.9% by weight of the composition depending upon the particular surfactants used and the effects desired. Preferably, the detersive surfactants comprise from about 5% to about 80% by weight of the composition. The detersive surfactant can be nonionic, anionic, ampholytic, zwitterionic, or cationic. Mixtures of these surfactants can also 5 be used. Preferred detergent compositions of the present invention combine the cost-effectiveness of anionic surfactants with the increased compatibility of the anionic oligomeric esters of the invention with such surfactants. Preferred detergent compositions comprise anionic detersive surfactants or mixtures of anionic 10 surfactants with other surfactants, especially nonionic surfactants. Nonlimiting examples of surfactants useful herein include the conventional C..-C. D alkyl benzene sulfonates and primary and 11 o random alkyl sulfates, the C 10 -C 18 alkyl alkoxy sulfates, the 15 c ιo~ C i8 ^ polyglycosides and their corresponding sulfated polyglycosides, C ^ -C.g alpha-sulfonated fatty acid esters, C.--C _ alkyl and alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy) , ^i^^i δ hetaines and sulfobetaines ("sultaines") , C. Q - .- amine oxides, and the like. Other conven- 20 tional useful surfactants are listed in standard texts. One particular class of adjunct nonionic surfactants especially useful herein comprises the polyhydroxy fatty acid amides of the formula: wherein: R is H, C.-C 8 hydrocarbyl, 2-hydroxyethyl, 2-hydroxy- propyl, or a mixture thereof, preferably C -C. alkyl, more prefer¬ ably C. or C- alkyl, most preferably C. alkyl (i.e., methyl); and R is a C 5 - __ hydrocarbyl moiety, preferably straight chain C_- 3 0 alkyl or alkenyl, more preferably straight chain C-- .- alkyl or alkenyl, most preferably straight chain alkyl or alkenyl, or mixture thereof; and Z is a polyhydroxyhydrocarbyl moiety having a linear hydrocarbyl chain with at least 2 (in the case of glyceraldehyde) or at least 3 hydroxyls (in the case of other 3 5 reducing sugars) directly connected to the chain, or an alkoxylated derivative (preferably ethoxylated or propoxylated) thereof. Z preferably will be derived from a reducing sugar in a reductive amination reaction; more preferably Z is a glycityl moiety. Suitable reducing sugars include glucose, fructose, maltose, lactose, galactose, mannose, and xylose, as well as glyceraldehyde. As raw materials, high dextrose corn syrup, high fructose corn syrup, and high maltose corn syrup can be utilized as well as the individual sugars listed above. These corn syrups may yield a mix of sugar components for Z. It should be understood that it is by no means intended to exclude other suitable raw materials. Z preferably will be selected from the group consisting of -CrL- (CHOH)-CH-OH, where n is an integer from 1 to 5, inclusive, and R' is H or a cyclic mono- or poly- saccharide, and alkoxylated derivatives thereof. Most preferred are glycityls wherein n is 4, particularly -Cr -(CHOH) -CH OH. In Formula (I) , R can be, for example, N-methyl, N-ethyl, N-prcpyl, N-isαpropyl, N-butyl, N-isobutyl, N-2-hydroxy ethyl, or N-2-hydrαxy prσpyl. Far highest sudsing, R is preferably methyl or hydroxyalkyl. If lower sudsing is desired, R is preferably C_-Cg alkyl, especially n-propyl, iso-propyl, n-butyl, iso-butyl, peπtyl, hexyl and 2-ethyl hexyl. R -co* can be, for example, cocamide, stearamide, oleamide, lauramide, myristamide, capricamide, palmitamide, tallowamide, etc. Detergent Builders - Optional detergent compositions of the present invention contain inorganic and/or organic detergent builders to assist in mineral hardness control. If used, these builders σcπprise from about 5% to about 80%, preferably from about 10% to about 50% by weight of the compositions. Inorganic detergent builders include, but are not limited to, the alkali metal, ammonium ' and alkanolammonium salts of polyphos- phates (exemplified by the tripolyphosphates, pyrophosphates, and glassy polymeric meta-phosphates) , phosphonates, phytic acid, silicates, carbonates (including bicarbonates and sesquicarbon- ates) , sulphates, and aluminosilicates. However, non-phosphate builders are required in some locales. Examples of silicate builders are the alkali metal silicates, particularly those having a Sio :Na 0 ratio in the range 1.6:1 to 3.2:1 and layered silicates, such as the layered sodium silicates described in U.S. Patent 4,664,839, issued May 12, 1987 to H. P. Rieck, available from Hoechst under the trademark "SKS"; SKS-6 is an especially preferred layered silicate builder. Exanples of carbonate builders are the alkaline earth and alkali metal carbonates as disclosed in German Patent Application No. 2,321,001 published on November 15, 1973. Aluminosilicate builders are especially useful in the present invention. Preferred aluminosilicates are zeolite builders which have the formula: Na s [(A10 2 ) z (SiO^-x^O wherein z and y are integers of at least 6, the molar ratio of z to y is in the range from 1.0 to about 0.5, and x is an integer from about 15 to about 264. Useful aluminosilicate ion exchange materials are commercially available. These aluminosilicates can be crystalline or amorphous in structure and can be raturally-occurring aluminosilicates or synthetically derived. A method for producing aluminosilicate ion exchange materials is disclosed in U.S. Patent 3,985,669, Krummel, et al, issued October 12, 1976. Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the designations Zeolite A, Zeolite P (B) , and Zeolite X. Organic builders include, but are not limited to polvcarbαxylate ccmpounds such as ether polycarboxylates and ether hvdrαxypolvcarbαxylates, copolymers of maleic anhydride with ethylene or vinyl methyl ether, 1, 3, 5-trihydroxy benzene-2, 4, 6-trisulphαnic acid, carboxymethyloxysuccinic acid, the various alkali metal, ammonium and substituted ammonium salts of polyacetic acids such as ethylenediamine tetraacetic acid and nitrilotriacetic acid, as well as polycarboxylates such as mellitic acid, succinic acid, oxydisuccinic acid, polymaleic acid, benzene 1,3,5-tricar- bαxylic acid, carboxymethyloxysuccinic acid, and soluble salts thereof. Citrate builders, e.g., citric acid and soluble salts thereof (particularly sodium salt) , are preferred polycarboxylate builders that can also be used in granular compositions, especially in combination with zeolite and/or layered silicate builders. Also suitable in the detergent compositions of the present invention are the 3,3-dicarboxy-4-oxa-l,6-hexanedioates and the related σαmpounds disclosed in U.S. Patent 4,566,984, Bush, issued January 28, 1986. Useful succinic acid builders include the C 5 -C 2 o alkyl and alkenyl succinic acids and salts thereof. Fatty acids, e.g., C - monocarboxylic acids, can also be incorporated into the compositions alone, or in combination with the aforesaid builders, especially citrate and/or the succinate builders, to provide additional builder activity. Such use of fatty acids will generally result in a reduction of sudsing, which should be taken into account by the formulator. In situations where phosphorus-based builders can be used, and especially in the formulation of bars used for hand-laundering operations, the various alkali metal phosphates such as the well-kncwn sodium tripolyphosphates, sodium pyrophosphate and sodium orthophosphate can be used. Phosphorate builders such as ethane-l-hydroxy-l,l-diphosphonate and other known phosphorates (see, for example, U.S. Patents 3,159,581; 3,213,030; 3,422,021; 3,400,148 and 3,422,137) can also be used. Optional Detergent Ingredients - In addition to surfactants and builders, the compositions herein can optionally include one or more conventional detergent adjunct materials or other materials for assisting αr enhancing cleaning performance, treatment of the substrate to be cleaned, or to modify the aesthetics of the detergent coπposition. Other optional ingredients which can be included in detergent compositions of the present invention, in their conventional art-established levels for use (generally from 0 to about 20% of the detergent composition) , include solvents, hydrotropes, solubilizing agents, soil release agents, chelating agents, clay soil removal/anti-redeposition agents, polymeric dispersing agents, processing aids, antitarnish and/or anti-cor¬ rosion agents, dyes, fillers, optical brighteners, germicides, pH-adjusting agents (monoethanolamine, sodium carbonate, sodium hydroxide, etc.), perfumes, fabric softening components, static control agents, bleaching agents, bleach activators, bleach stabilizers, suds suppressors, suds boosters, and the like. Detersive Ehzv es - Optionally, the compositions employed in the present invention comprise detersive enzymes. Detersive enzymes are included for a wide variety of fabric laundering purposes, including removal of protein-based, carbohydrate-based, or triglyceride-based stains, for example, and for the prevention of refugee dye transfer. The enzymes to be incorporated include proteases, a ylases, lipases, cellulases, and peroκidases, as well as mixtures thereof. Other types of enzymes may also be included. They may be of any suitable origin, such as vegetable, animal, bacterial, fungal and yeast origin. However, their choice is governed by several factors such as pH-activity and/or stability optima, thermostability, stability versus active detergents, builders and so on. In this respect bacterial or fungal enzymes are preferred, such as bacterial amylases and proteases, and fungal cellulases. Enzymes are normally incorporated at levels sufficient to provide up to abcut 5 mg by weight, more typically about 0.01 mg to about 3 mg, of active enzyme per gram of the composition. Stated otherwise, the compositions herein will typically comprise from about 0.001% to about 5%, preferably 0.01%-1%, by weight of a commercial enzyme preparation. Enzymes are usually present in such ccmmercial preparations at levels sufficient to provide from 0.005 to 0.1 Anson units (AU) of activity per gram of coπposition. A wide range of enzyme materials and means for their incorp¬ oration into synthetic detergent granules is disclosed in U.S. Patent 3,553,139, issued January 5, 1971 to McCarty et al. Enzymes are further disclosed in U.S. Patent 4,101,457, Place et al, issued July 18, 1978, and in U.S. Patent 4,507,219, Hughes, issued March 26, 1985. Enzymes for use in detergents can be stabilized by various techniques. Enzyme stabilization techniques are disclosed and exemplified in U.S. Patent 4,261,868, issued April 14, 1981 to Horn, et al, U.S. Patent 3,600,319, issued August 17, 1971 to Gedge, et al, and European Patent Application Publication No. 0199405, Application No. ' 86200586.5, published October 29, 1986, Venegas. Enzyme stabilization systems are also described, for example, in U.S. Patents 4,261,868, 3,600,319, and 3,519,570. All above disclosures are incorporated herein by reference. Methods of Use - The dispersing agents of the invention, at cxincentrations in an aqueous fabric laundering liquor of at least about 1 ppm, preferably from about l to about 50 ppm, and most preferably about 5 to about 30 ppm, provide effective, combined cleaning and soil dispersing treatments for fabrics washed in an aqueous, preferably alkaline (pH range about 6.5 to about 11, more preferably about 7 to about 10.5) environment, in the presence of typical detergent ingredients. Surprisingly (especially insofar as pH and anionic surfactant are concerned) , all of the above-identified detergent ingredients can be present in the wash water at their art disclosed levels to perform their conventional tasks, e.g., for cleaning and softening fabrics or the like, without ill-effects on the soil dispersing properties of the esters. The method of washing fabrics with the dispersing agents siπply comprises contacting said fabrics with an aqueous laundry liquor containing the conventional detersive ingredients described hereinabove, as well as the above-disclosed effective levels of dispersing agent. Although this method is not especially limited in terms of factors such as pH and surfactant types present, it should be appreciated that for best cleaning of fabrics, it is often especially desirable to make use in the laundry process of anionic surfactants, such as conventional linear alkylbenzene sulfonates and also to use higher pH ranges as defined above. Thus, a preferred method for an optimized combination of cleaning and soil dispersing provided by the invention constitutes using all of the following: the preferred levels of dispersing agent (5-30ppm) ; anionic surfactant; pH of from about 7 to about 10.5. Cleaning benefits are surprisingly obtainable after a single use/laundry cycle comprising the following steps: a) exposing said fabrics to soiling through normal wear or use; b) contacting said fabrics with said aqueous laundry liquor by soaking or by hand-washing or in an automatic washing machine far periods ranging from about 5 minutes to about 15 hours; c) rinsing said fabrics with water; and d) line- or tumble-drying said fabrics. In the above, step (b) includes both hand-washing and typical U.S., Japanese, or European washing machines operating under their conventional conditions of time, temperature, fabric load, amounts of water and laundry product concentrations. The detergent can be introduced to the system either by liquid or granular detergent or by synthetic detergent bar. Also, in step (d) , the "txmtole-drying" to which is referred involves use of conventional brands of programmable laundry dryers (these are occasionally integral with the washing machine) using their conventional fabric loads, temperatures and operating times. The following nonlimiting examples illustrate the use of a typical ester composition of the invention as a dispersing agent for thru-the-wash application to a variety of fabrics. The compositons and processes herein are especially useful for hand- wash, but are also useful in any fabric laundering process which employs low fabric:water ratios, such as the concentrated laundering processes described in U.S. Patents 4,489,455 and 4,489,574, both issued to Spendel, Dec. 25, 1984. EXAMPLE VII A granular detergent composition is prepared comprising the following ingredients and an ester composition prepared following the procedures set forth in Example IV. OuHUJonent Weight % C.- linear alkyl benzene sulfonate 22 Phosphate (as sodium tripolyphosphate) 30 Sodium carbonate 14 Sodium silicate 3 Zeolite A (0.1-10 microns) 8.2 Nonanσyloxybenzenesulfonate 3.2 Sodium percarbonate* 4.5 Chelant (diethylenetriaminepentaacetic acid) 0.4 Sodium sulfate 5.5 Dispersing agent (Example III) 0.4 Minors, filler** and water Balance to 100% * Average particle size of 400 to 600 microns. **Can be selected from convenient materials such as CaCO , talc, clay, silicates, and the like. In testing the soil dispersing performance of the dispersing agents, the following test method is used: White 100% cotton fabric, white polycotton fabric (50%/50% T-Shirt material) , and an all synthetic material (81% acrylic, 15% nylon, 4% Lycra) are used in the testing. Using a Sears KENMORE washer, the fabrics are desized with a ccmmercial granular detergent (DASH) . The washing is conducted in 0 grains per gallon (gpg) water at a temperature of 120°F (48.8°C) for 12 minutes, with subsequent rinsing in 0 gpg water at a temperature of 120°F (48.8°C). This desizing step is done twice and is followed by two additional wash cycles using only water. The desized fabrics are formed into swatches (5 inches square) . Testing is done in a 5 pot Automatic Mini-Washer (AMW) to mimic a hand-wash operation using standardized conditions. After the AMW pots are filled with 7.6 liters (2 gallons) of water each, the detergent composition (above) and the dispersing agent are added to each pot. The clean test swatches are then added alone with an amount of unwashed, dirty consumer ballast to bring the water/cloth ratio to the desired level of approximately 5:1 (liters:kg) . The consumer ballast is split into equal halves between the dispersing agent containing formula and a pot containing an identical control formula without dispersing agent. The wash cycle is conducted in 8 grains per gallon (gpg) water at a temperature of 77 F (25°C) water. The wash cycle consists of a 30 minute soak followed by 10 minute agitation. After the wash cycle, there is a 2 minute spin cycle, followed by two 2-minute rinse cycles using 8 gpg water at a temperature of 77°F (25°C) . For multi-cycle testing the test swatches are dried and the above steps repeated using the same test swatches and new dirty consumer bundles. At the end of the last rinse cycle, the test swatches are dried in a dryer. Tristiulus meter readings (L,a,b) are then determined for each test swatch. Whiteness performance in terms of Hunter Whiteness Values (W) is then calculated according to the following equation: W = (7L 2 - 40Lb)/700 The higher the value for W, the better the whiteness performance. All fabrics display significantly iirproved whiteness after laundering compared with fabrics which have not been exposed to the dispersing agents of this invention. EXAMPLE VTII A laundry bar suitable for hand-washing soiled fabrics is prepared by standard extrusion processes and comprises the following: Component Weight % C linear alkyl benzene sulfonate 30 Phosphate (as sodium tripolyphosphate) 7 Sodium carbonate 25 Sodium pyrophosphate 7 Coconut monoethanolamide 2 Zeolite A (0.1-10 micron) 5 Carboxymethylσellulose 0.2 Polyacrylate ( .w. 1400) 0.2 Dispersing agent (Example V) 0.5 Brightener, perfume 0.2 Protease 0.3 CaS0 4 1 MgS0 4 1 Water 4 Filler* Balance to 100% *Can be selected from convenient materials such as CaCO. talc. ■ v clay, silicates, and the like. In testing the soil dispersing performance of the dispersing agents, the test method used in Example VII is followed. All fabrics display significantly improved whiteness after laundering compared with fabrics which have not been exposed to the esters of the invention. EXAMPLE IX A liquid detergent composition is prepared comprising the following ingredients and an ester composition prepared following the procedures set forth in Example IV. Oomponent Weight % C i4-15 a ^ y polyethoxylate (2.25) sulfonic acid 10 C ιp ,- linear alkylbenzene sulfonic acid 8.5 C 12-13 alkyl polyethoxylate (6.5) 2.4 Sodium cumene sulfonate 2.1 Ethanol 1.2 1,2 propanediol 5 Sodium hydroxide 1.9 Monoethanolamine 2.4 Citric acid 1.5 C _ . fatty acid 1.9 Dispersing agent (Example III) 1.5 Brightener 0.l Minors, filler* and water Balance to 100% *Can be selected frαti convenient materials such as CaCO , talc, clay, silicates, and the like. In testing the soil dispersing performance of the dispersing agents, the test method used in Example VII is followed. All fabrics display significantly improved whiteness after laundering compared with fabrics which have not been exposed to the esters of the invention. EXAMPLE X A concentrated liquid detergent composition is prepared comprising the following ingredients and an ester composition prepared following the procedures set forth in Example III. Component Weight % C 15 alkyl polyethoxylate (2.25) sulfonic acid 10.6 C 12-13 ^■^ near alkylbenzene sulfonic acid 12.5 C 12-13 aIk Y 1 Polyethoxylate (6.5) 2.4 Sodium cumene sulfonate 6 Ethanol 1.5 1,2 propanediol 4 Sodium hydroxide 0.3 Monoethanolamine 1 C 12-14 fatty acid 2 Dispersing agent (Example II) 1.5 Minors, filler* and water Balance to 100% *Can be selected from convenient materials such as CaCO , talc, clay, silicates, and the like. In testing the soil dispersing performance of the dispersing agents, the test method used in Example VII is followed. All fabrics display significantly ijrproved whiteness after laundering compared with fabrics which have not been exposed to the esters of the invention. While the compositions and processes of the present invention are especially useful in hand-wash fabric laundering cperations, it is to be understood that they are also useful in any cleaning system which involves low water:fabric ratios. One such system is disclosed in U.S. Patent 4,489,455, Spendel, issued Dec. 25, 1984, which involves a washing machine apparatus which contacts fabrics with wash water containing detersive ingredients using a low water: fabric ratio rather than the conventional method of immersing fabrics in an aqueous bath. Typically, the ratio of water:fabric ranges from about 0.5:1 to about 6:1 (liters of waterrkg of fabric) . EXAMPLE XI Using the machine and operating conditions disclosed in U.S. Patent 4,489,455, cited above, 25 grams of a composition according to Example VTI herein are used to launder fabrics. If desired, sudsing of the composition can be minimized by incorporating therein from 0.2% to 2% by weight of a fatty acid, secondary alcohol, or silicone suds controlling ingredient. Dishwashing Compositions Another aspect of the present invention relates to dishwashing compositions, in particular automatic and manual dishwashing compositions, especially manual liquid dishwashing compositions. Liquid dishwashing compositions according to the present invention preferably comprise from at least about 0.1%, more preferably from about 0.5% to about 30%, most preferably frcrn about 1% to about 15% of the partially oligomerized ester and from about 1% to about 99.9% of a detersive surfactant. Liquid dishwashing compositions according to the present invention may comprise any of the ingredients listed herein above. in addition the dishwashing compositions may comprise other ingredients such as bactericides, chelants, suds enhancers, opacifiers and calcium and magnesium ions. Hydrotropes - A hyαrotrope is typically added to the compositions of the present invention, and may be present at levels of from about 0% to about 10%, preferably from about 1% to about 5%, by weight. Useful hydrotropes include sodium, potassium, and ammonium xylene sulphαnates, sodium, potassium, and ammonium toluene sulphαnate, sodium, potassium and ammonium cumene sulphonate, and mixtures thereof. Other compounds useful as hydrotropes herein include polycarboxylates. Some polycarboxylates have calcium chelating properties as well as hydrotropic properties. An example of a commercially available alkylpolyethoxy polycarboxylate which can be employed herein is POLY-TERGEMT C, Olin Corporation, Cheshire, CT. Another compound useful as a hydrotrope is alkyl a phodi- carboxylic acid of the generic formula: (CH2)X CCO- RCNHCH2CH2N< (CH2)x CCOM wherein R is a C. to C 8 alkyl group, x is from 1 to 2, M is preferably chosen from alkali metal, alkaline earth metal, ammonium, mono-, di-, and tri-ethanolammonium, most preferably from sodium, potassium, ammonium, and mixtures thereof with magnesium ions. The preferred alkyl chain length (R) is a C.. to C alkyl group and the dicarboxylic acid functionally is diacetic acid and/or dipropionic acid. A suitable example of an alkyl amphodicarboxylic acid is the amphσteric surfactant Miranol R 2CM Gone, manufactured by Miranol, Inc., Dayton, NJ. Organic solvent The compositions of the invention will most preferably contain an organic solvent system present at levels of from about 1% to about 30% by wei«ght, preferably from abcut 1% to about 20% by weight, more preferably from about 2% to about 15% by weight of the composition. The organic solvent system may be a mono, or mixed solvent system. Preferably, at least the major component of the solvent system is of low volatility. Suitable organic solvents for use herein has the general formula: R' RO(Oi CHO) n Η wherein R is an alkyl, alkenyl, or alkyl aryl group having from about 1 to about 8 carbon atoms, R' is either H or Ctr, and n is an integer from 1 to 4. Preferably, R is an alkyl group containing l to 4 carbon atoms, and n is 1 or 2. Especially preferred R groups are n-butyl or iso- butyl. Preferred solvents of this type are l-n-butαxyprαpane-2-ol (n=l) ; and l(2-n-butoxy-l-methylethoxy)- propane-2-ol (n=2) , and mixtures thereof. Other solvents useful herein include the water soluble CARBITOL or CELLOSOLVE solvents. These solvents are compounds of the 2-(2-alkoxyethoxy)ethanol class wherein the alkoxy group is derived frαn ethyl, propyl or butyl. Other suitable solvents are benzyl alcohol, and diols such as 2-ethyl-l,3-hexanediol and 2,2,4-trimethl-l,3-pentanediol. The low molecular weight, water-soluble, liquid polyethylene glycols are also suitable solvents for use herein. The alkane mono and diols, especially the C1-C6 alkane mono and diols are suitable for use herein. C1-C4 monohydric alcohols (eg: ethanol, propanol, isopropanol, butanol and mixtures thereof) are preferred, with ethanol particularly preferred. The C1-C4 dihydric alcohols, including propylene glycol, are also preferred. Thickening agents - The compositions acx∞rding to the present invention may additionally comprise thickening agents, such as polyquateriura cellulose cationic polymer, for example QuatrisoftR available from the Americhol Corporation. Calcium - Compositions according to the present invention may optionally comprise from about 0.01% to about 3%, more preferably from about 0.15% to about 0.9% of calcium ions. The calcium ions can, for example, be added as a chloride, hydroxide, oxide, formate or acetate, or nitrate salt. If the anionic surfactants are in the acid farm, the calcium can be added as a calcium oxide or calcium hydroxide slurry in water to neutralise the acid. The calcium ions may be present in the compositions as salts. The amount of calcium ions present in compositions of the invention nay be dependent upon the amount of total anionic surfactant present herein. The molar ratio of calcium ions to total anionic surfactant is preferably from about 1:0.1 to about 1:25 more preferably from about 1:2 to about 1:10, for compositions of the invention. Calcium stabilising agent - In order to provide good product stability, and in particular to prevent the precipitation of insoluble calcium salts malic, maleic or acetic acid, or their salts, or certain lime soap dispersant compounds may be added to the composition of the present invention comprising calcium . Where calcium is present, malic, maleic or acetic acid, or their salts can be added at levels of from about 0.05% to about 10% of the composition and a molar ratio with calcium of from about 10:1 to about 1:10. Magnesium - From about 0.01% to about 3%, most preferably from about 0.15% to about 2%, by weight, of magnesium ions are preferably added to the liquid detergent compositions of the invention for improved product stability, as well as improved sudsing. If the anionic surfactants are in the acid form, then the magnesium can be added by neutralisation of the acid with a magnesium oxide or magnesium hydroxide slurry in water. Calcium can be treated similarly. This technique minimizes the addition of chloride ions, which reduces corrosive properties. The neutralized surfactant salts and the hydrotrope are then added to the final mixing tank and any optional ingredients are added before adjusting the pH. pH of the Oumnositions - The composition according to the present invention formulated for use in manual dishwashing applications are preferably formulated to have a pH at 20°C of from about 3 to about 12, preferably from about 6 to about 9, most preferably from about 7 to about 8.5. In another aspect of the present invention the dishwashing composition may be formulated for use as in pre-treatment applications whereby the composition is applied in essentially the concentrated farm onto the dishes. Preferably the composition is <allowed to remain on the dishes for a period of time. Compositions for use in such .applications preferably have a pH of from about 3 to about 14, more preferably from about 3 to about 5 or greater than about 8. Examples XII The following liquid compositions of the present invention are prepared by mixing the listed ingredients in the given amounts. b wei ht of the total cαπposition C12/13 alkylethαxysulphate C8 alkylsulphate ♦Dispersing agent (ex. Ill) ave. C12/14 alkyl amine oxide ave. C16 alkyl amine oxide C12/14 alkyl dimethyl betaine ★ Dispersing agent having a σorpletion index of 2.3 and an EG/PG = 1.5. The dispersing agent used in the above examples may be replaced by any of the dispersing agents described herein. WHAT IS CLAIMED IS:

Claims: WHAT IS CLAIMED IS : 1. A method for cleaning fabrics, said method comprising contacting said fabrics in an aqueous liquor comprising conventional detergent ingredients and at least 1 ppm of a dispersing agent which comprises a mixture of: A) from 0% to 95% of folly oligomerized esters of the formula: (CAP) (EG PG) (T) (SI) 2 v y z wherein i) (CAP) represents sulfonated end-capping units selected from the group consisting of: (a) MO S(CH ) (CH CH O)(RO) -, wherein M is a salt-forming cation, R is 3 2 m 2 2. n ethylene or propylene or a mixture thereof, m is 0 or 1, and n is from 0 to 4; (b) sulfobenzoyl units of the formula (MO S)(C H )C(O)-, wherein M is a salt- 3 6 4 forming cation; and (c) mixtures of (a) and (b); ii) (EG/PG) represents oxyethyleneoxy units, oxy-l,2-propyleneoxy units, or mixtures thereof; iii) (T) represents terephthaloyl units; and, optionally, iv) (SI) represents 5-sulfoisophthaloyl units of the formula - (O)C(C H )(SO M)C(O)-, wherein M is a salt-forming cation; v is from 0.25 to 50, y is from 1.25 to 30, and z is determined by the formula y/(z+l) - 1.25 to 5; wherein, v, y and z represent the average number of moles of the corresponding units per mole of said ester; and B) from 5% to 100% of partially oligomerized esters of A) with a number average molecular weight of no more than 70% of the molecular weight of the folly oligomerized esters, A); such that the number average molecular weight of the dispersing agent is from 400 to 3,000. 2. The method according to Claim 1, wherein the (CAP) units are i)(a) and v is determined by the formula v = y+z to y+z-1. 3. The method according to Claim 1, wherein the (CAP) units are i)(b) and v is determined by the formula v = y+z+1. 4. The method according to Claim 1, wherein the (CAP) units are i)(c) and v is determined by the formula v = y+z+1. 5. The method according to Claim 1 wherein said ester composition has a number average molecular weight of from 500 to 1,100 and wherein said detergent ingredients comprise from 5% to 80% by weight of detersive surfactant. 6. The method according to Claim 5 wherein said detergent ingredients further comprises from 5% to 80% by weight detergent builder and from 0% to 20% of conventional detersive adjuncts. 7. The method according to Claim 6, wherein said fabrics are subjected to one or more cycles each comprising the following steps: (A) exposing said fabrics to soiling through wear or use; (B) contacting said fabrics with said laundry liquor for periods ranging from 5 minutes to 15 hours; (C) rinsing said fabrics with water; and (D) line- or tumble-drying said fabrics. 8. A method of hand-washing fabrics according to Claim 7 comprising contacting and agitating by hand fabrics in an aqueous laundry liquor comprising at least 300 ppm of said laundry detergent and at least 1 ppm of said dispersing agent. 9. A method for dispersing soils in an aqueous laundry liquor comprising contacting fabrics in an aqueous laundry liquor comprising at least 1 ppm of said dispersing agent which is further characterized in that it consists essentially of the oligomeric product of reacting compounds comprising: (A) monovalent cation salts of said sulfonated end-capping monomers; (B) dimethyl terephthalate; (C) dimethyl sulfoisophthalate; and (D) ethylene glycol, propylene glycol or a mixture thereof; and said aqueous laundry liquor is further characterized in that it has a pH from 7 to 11. 10. A method according to Claim 9 wherein said oligomeric product comprises: (A) 1 mole of monovalent cation salts of said sulfonated end-capping monomers; (B) 5 moles of dimethyl terephthalate; (C) 1 mole dimethyl sulfoisophthalate; and (D) 12 moles of ethylene glycol, propylene glycol or a mixture thereof 1 1. A detergent composition in granule form comprising: i) from 1% to 99.9% by weight of a detersive surfactant; and ii) at least 0.1% by weight of a dispersing agent comprising: a) from 0% to 95% by weight of folly oligomerized esters of the formula: CH2CH2-0-(!- (C6H )Sθ3Na b) from 5% to 100% by weight of partially oligomerized esters of ii)a) with a Completion Index of 6. 12. A detergent composition in bar form comprising: i) from 1% to 99.9% by weight of a detersive surfactant; ii) at least 0.1% by weight of a dispersing agent comprising: a) from 0% to 95% by weight of folly oligomerized esters of the formula: )S03N and b) from 5% to 100% by weight of partially oligomerized esters of ii)a) with a Completion Index of approximately 6. 13. A detergent composition in liquid form comprising: i) from 1% to 99.9% by weight of a detersive surfactant; ii) at least 0.1% by weight of a dispersing agent comprising: a) from 0% to 95% by weight of folly oligomerized esters of the formula: and b) from 5% to 100% by weight of partially oligomerized esters of ii)a) with a Completion Index of approximately 3. 14. A method for modifying isethionate comprising reacting an excess of polyol reactant with isethionate. 15. A method according to Claim 14 wherein said polyol reactant and said isethionate are present in a molar ratio of at least 2: 1. 16. A liquid dishwashing detergent composition comprising from 1% to 99.9% of a detersive surfactant and at least 0.1% of an ester composition comprising: A) from 0% to 95% of folly oligomerized esters of the formula: (CAP) 2 (EG/PG) v (T) y (SI) 2 wherein i) (CAP) represents sulfonated end-capping units selected from the group consisting of: (a) MO3S(CH2) m (CH2CH2O)(RO) n ., wherein M is a salt-forming cation, R is ethylene or propylene or a mixture thereof, m is 0 or 1, and n is from 0 to 4; (b) sulfobenzoyl units of the formula (MO3S) (CgH^CO)-, wherein M is a salt-forming cation; and (c) mixtures of (a) and (b); ii) (EG PG) represents oxyethyleneoxy units, oxy-l,2-propyleneoxy units, or mixtures thereof; iii) (T) represents terephthaloyl units; and, optionally, iv) (SI) represents 5-sulfoisophthaloyl units of the formula - (0)C(C6H3)(SO3M)C(0 , wherein M is a salt-forming cation; v is from 0.25 to 50, y is from 1.25 to 30, and z is determined by the formula y/(z+l)=1.25 to 5; wherein, v, y and z represent the average number of moles of the corresponding units per mole of said ester; and B) from 5% to 100% of partially oligomerized esters of A) with a number average molecular weight of no more than 70% of the molecular weight of the folly oligomerized esters, a); such that the number average molecular weight of the dispersing agent is from 400 to 3,000.

Inventors: GOSSELINK EUGENE PAUL, WATSON RANDALL ALAN, GOSSELINK, EUGENE, PAUL, WATSON, RANDALL, ALAN
Applicants: PROCTER & GAMBLE, THE PROCTER & GAMBLE COMPANY
Application year: 1994
Main classification: C08G63
IPC codes: C08G63, C08K5, C08L67, C11D3